The effect of mechanically milled lead iodide powder on perovskite film morphology

Mechanical milling pretreatment was introduced to obtain a nano-sized PbI2 powder, promoting high-quality CH3NH3PbI3 perovskite films. The structure and microstructure of milled PbI2 powder were investigated using Transmission electron microscope (TEM), Brunauer–Emmett–Teller surface adsorption (BET), and X-ray diffraction (XRD) employing the Rietveld refinement method. The nano-sized PbI2 powder in the precursor solution has revealed a significant impact on the morphology of PbI2 films, resulted in approximately full coverage, smooth and high-quality film. The quality and purity of generated perovskite films were significantly dependent on the morphologies and quality of PbI2 precursor film. A good perovskite film with complete conversion, small particle size distribution, and appreciation coverage has corresponded to the high-quality PbI2 film. Toward low-cost Perovskite solar cells ((PSCs), as no precious metals and expensive hole transport materials are required, a TiO2/CH3NH3PbI3/carbon device was fabricated in the air via a two-step dipping method. Based on milled PbI2 powder (9 h), the perovskite device achieved a Power conversion efficiency (PCE) of 5.8%, while that based on unmilled PbI2 obtained 2.55%. This enhanced performance is attributed to the benefits of milling PbI2 powder, resulting in a small crystallite size with a high surface area and a high-quality perovskite film with good coverage.